Neutron scattering techniques in the study of solid-state ion-conducting materials



Sunday, 18 June; 15:25 - 18:10 in Room A5, Hall 7 of "Padova Fiere"

Tutorial Description

Neutron techniques offer distinct advantages for structural and dynamic investigations of materials. Because neutrons scatter from the nucleus, alternative and complementary contrast compared to photons or electrons are achieved, with particular relative sensitivity to elements with low atomic number or neighboring elements. Also, isotopes of many elements have vastly different scattering cross sections. Controlling the isotope ratio of these elements allows researchers to highlight specific elements in a crystal structure or features at interfaces. Isotopic substitution can be used to label a reactant to determine how it contributes to the products incorporated into the sample. Because neutrons also have a magnetic moment, they are highly sensitive to magnetism in materials. Due to its large mass, the energy of a neutron is similar to that of many dynamical processes in materials, such as vibrations and diffusion, meaning that the neutrons can exchange energy with the sample and information about dynamics with energy resolution on the order of meV to neV can be routinely obtained. Because neutrons are weakly interacting particles, they are non-destructive, with no ionization or local heating, and can easily penetrate thick solid materials. This promotes both robust in-operando and multi-modal sample. Neutrons also probe the entire sample providing statistical ensemble averages of structures.

Three techniques will be discussed. Neutron reflectometry provides accurate depth profiles of thin films and interfaces with sub-nanometer precision under in-operando condition of active material in their native environments. Neutron diffraction and pair distribution function (PDF) analysis take advantage of the sensitivity to light elements and isotopes to determine the average and the local crystal structures, respectively, in bulk materials with a relatively simple application under “in-operando” and “in-situ” conditions. PDF analysis is also highly sensitive to crystal defects and deviations from the average structure which have a great impact on the performance of ion conductors. Inelastic neutron scattering is used to study collective excitations, like phonons or magnons, in solid state materials. More interestingly, quasielastic scattering, with close to zero energy transfer, can characterize, diffusive processes. This is particularly useful for the study of dynamics in liquids but also for the diffusion of ions in ionic conductors for example.

Duration: 3 hours.

Registration: 150 Euros.

Tutorial Topics:

Dr. Joe Dura is a staff scientist at the NIST Center for Neutron Research. He received his Ph.D. in Physics from the University of Illinois at Urbana-Champaign. His research focusses on Neutron Reflectometry instrumentation methodology and applying this to characterize a wide variety of interfaces and thin films predominantly electrochemical materials and interfaces as well as hydrogen interactions with materials. He is on the Steering committee of CREB, the Center for Research in Extreme Batteries, and the Advisory Board for the International Symposium for Polymer Electrolytes

Dr. Maths Karlsson received in 2007 his Ph.D. in Physics from Chalmers University of Technology, where he has chosen to continue his career after three years (2008-2010) at the European Spallation Source. His research centers on investigations of fundamental key aspects of structure and dynamics of energy relevant - mostly hydrogen containing - oxides, such as proton and hydride-ion conductors, with a view towards technological applications. The research is mainly experimental in nature and involves as the primary tools neutron scattering and vibrational spectroscopy.

Dr. Lorenzo Malavasi is professor of materials chemistry at the University of Pavia, Italy. He is working in several areas of solid-state chemistry (electrolytes and cathodes for clean energy, hybrid organic-inorganic perovskites, and high-temperature superconductors) with particular interest in the investigation of structure–properties correlation by means of neutron and synchrotron diffraction and pair distribution function analysis. He is author of more than 130 papers in the field of materials and solid state chemistry.